Computer screens and other two-dimensional (2D) surfaces are commonly used for displaying 2D visual content such as a page of text, a diagram or a Web site page. Some forms of visual content contain two or more content forms, such as a page consisting of text and diagrams, or a Web site page containing information related to the site and unrelated advertising. Usually, only one page is displayed on a screen at a time and the page is confined to the boundaries of the screen. The different elements in a page must therefore compete with each other for space and the viewer's attention, even if they are related to each other. Existing Web site pages are therefore generally overcrowded by advertising and this is the major reason why Web advertising is presently considered ineffective.
Changing a displayed page (known as browsing or navigating) is a discontinuous process wherein an initially displayed page is removed from the screen and a second page is subsequently displayed. The ability to view only one page at a time makes it difficult for a viewer to know his location at a website and also creates uncertainty while navigating through the site. Changes in the size of a page are also made in discrete steps, and a return to the browser is required for each step change.
Another form of browsing allows a user to maintain several pages and websites concurrently browsable. For example, it is known to arrange several pages in a virtual three-dimensional (3D) space and projecting a portion of the 3D space onto the 2D screen. A viewer may continuously navigate from page to page. Such methods are disclosed, for example, in Robertson et al (Data Mountain: using Spatial memory for document Management) Robertson et al (Task Gallery: a 3D Window Manager) and in Applicant's publication WO02/095685.